This invention concerns a local area wireless network using optical fibers for distributing signals to and from short range antenna stations. A semiconductor laser is mounted in a connector housing for illuminating the angled end of an optical fiber in a connector for minimized reflection interference. A photodiode is also used for receiving signals from an optical fiber. A "connectorized" photodiode is a photodiode mounted in an electrical or optical fiber connector.
Wireless cellular telephone and similar communication systems have proliferated rapidly and are expected to expand dramatically in numbers of users. Furthermore, whereas present cellular telephone systems have a limited capacity sufficient for voice communications and limited handling of data, much broader band systems are expected for handling vast amounts of information for personal and business communications. New systems are needed for this expanding utilization.
It is common practice to increase the overall system capacity by dividing the system into ever smaller cellular units known as microcells. Optical fibers have heretofore been used to interconnect cellular base stations with large microcells, but it has not been considered cost effective to use fiber optics for smaller microcells. Thus, a low cost optical fiber signal distribution system is desirable for use in such microcells or for local area distribution of other RF signals.
In an RF signal distribution system, an individual building or a campus of buildings might, for example, have numerous short range RF antennas scattered within the building or buildings. Communications from outside this microcell or group of microcells are to and from a base station which is connected to an RF signal distribution hub for the building or buildings. Signals are transmitted and received between the hub and the scattered RF antennas for communicating with telephones or data transceivers within the microcell. Such a local network may also serve as a wireless PBX or LAN for communications within the microcell.
There are a number of advantages to such a system. For example, by handling some of the communication paths in a microcell instead of an entire cell of a cellular system, the capacity of the cell can be increased. The bandwidth that can be used for data transmission can be larger when such local area networks are used. Since a telephone or other portable device needs to communicate only over a short range, its power requirements can be decreased, thereby increasing its battery lifetime.
It is important, however, since a large number of antenna stations are needed in such a microcell, that each of the stations have a low cost. This low cost includes not only the components used, but also the ease of assembling a system with a few standardized devices to keep assembly and installation costs low.
It would be desirable to have a low cost reliable optical fiber system for such an RF signal distribution system for a number of reasons. Optical fibers and the lasers and photodetectors used with them are capable of handling very high data rates at low cost. The attenuation by fibers is very low; negligibly low for in-building distances. The RF levels at the antenna stations are therefore nearly independent of their distance from a distribution hub. Fiber is light, flexible and requires relatively little labor to install. Special electrical shielding is not required for preventing radio interference. Such systems can operate with very high reliability and low power consumption. However, no suitable low cost fiber optic systems or components are known.